1. Field of the Invention
The present invention relates to a design support method and a design support program suitable for optimum design of a conveying path of an apparatus such as a copying machine, in which the behavior of a sheet member such as a sheet during conveying is analyzed by simulation.
2. Description of the Related Art
For design of a conveying path, it is preferable that the function of each designed component is studied under various conditions before it is actually manufactured, because the number of processes required for manufacturing and testing prototypes can be reduced and the development period and cost can be reduced. As techniques of making a computer simulate the behavior of a sheet on a conveying path in order to achieve the above-described objective, design support systems have been proposed as disclosed in Japanese Patent Application Laid-open Nos. H11-195052 and No. H11-116133. In the design support system, a flexible medium is expressed by finite elements by a finite element method, contacts of the flexible medium with guides and rollers along a conveying path are judged, and a motion equation is numerically solved to evaluate a conveying resistance and a contact angle of the flexible medium relative to guides and the like.
For example, a document by Kazushi YOSHIDA “The Japan Society of Mechanical Engineers (JSME) international Journal, 96-1530, C(1997), pp. 230-236” discloses an approach to improving a calculation speed by expressing a flexible medium simply by masses and springs.
A motion of a flexible medium is calculated through numerical time integral. Namely, a motion equation of a flexible medium expressed discretely by finite elements or a mass-spring system is established, an analysis time is divided into time steps having a finite width, and unknown values such as an acceleration, a speed and a displacement are sequentially calculated at each time step starting from time 0. Widely known as approaches to calculating these values are a Newmark-β method, a Wilson-θ method, an Euler method, a Kutta-merson method and the like.
The time taken to solve a motion equation of a flexible medium through numerical time integral may be several hours depending upon a simulation model scale and analysis conditions. It is therefore necessary to confirm whether there is any input error of a simulation model before the calculation of numerical integral starts.
A simulation model has information input in a conveying path definition step and a conveying condition setting step. The input content of the conveying path definition step is mainly position information. A straight line guide is expressed by the coordinate values of a start point and an end point, an arc guide is expressed by the coordinate values of a center, a radius, a start point angle and an end point angle, and a conveying roller is expressed by the coordinate values of a center and a radius.
As the input content of the conveying condition setting step, a conveying guide is expressed by a friction coefficient of a flexible medium, a conveying roller is expressed by a friction coefficient of a flexible medium and time sequential roller drive conditions for conveying the flexible medium.
In confirming a simulation model, position information on a guide and a roller is drawn on a display as a line segment, an arc or a circle in accordance with input coordinate values. A user is not required to read input values and can perform a confirmation work visually easily. A friction coefficient of a flexible medium is input as numerical values in some cases. However, generally, as the material quality of an object of a model is designated, an attribute of each material quality preset in a database is automatically selected and input to a system. It is therefore unnecessary for a user to perform a confirmation work.
However, in confirming conveying roller drive conditions set for conveying a flexible medium (in the following, a paper sheet is used by way of example) along a conveying path under desired conveying conditions, the following steps are required to be executed, resulting in a problem that the confirmation work is complicated and hard to understand.
(Confirmation of Sheet Conveying Direction)
First, description will be made on a confirmation work method regarding a sheet conveying direction.
1. If a pair of rollers is modeled overriding a conveying path, one being defined as a driving roller and the other being defined as a driven roller, it is confirmed that the drive condition is set to which roller (confirmation of the driving roller).
2. If a sign added to a numerical value of a roller rotation speed input for the driving roller is defined that a positive sign indicates a counter-clockwise rotation and a negative sign indicates a clockwise rotation, it is confirmed that which of the positive and negative numerical values is input (confirmation of a rotation direction of the driving roller).
3. It is confirmed that a nip portion of the driving roller and driven roller, i.e., a sheet on the conveying path, is conveyed to which direction (confirmation of a conveying direction of a sheet by a conveying portion).
These works are required for the pair of rollers to confirm only the sheet conveying direction. These works are sequentially performed from a roller pair disposed at the upstream side of the conveying direction to a roller pair disposed at the downstream side. The sheet conveying direction of the whole model cannot be confirmed visually and intuitively.
(Confirmation of Sheet Conveying Speed)
Next, description will be made on a confirmation work method regarding a sheet conveying speed.
1. If a pair of rollers is modeled overriding a conveying path, one being defined as a driving roller and the other being defined as a driven roller, it is confirmed that the drive condition is set to which roller (confirmation of the driving roller).
2. It is confirmed what numerical value of a rotation speed is input to the driving roller.
3. It is confirmed what radius is set to the driving roller.
4. A roller peripheral speed is calculated (confirmation of a sheet conveying speed).
A rotation speed of the driving roller is generally expressed by a rotation number of a roller shaft per unit, time from the viewpoint of drive system design. Even if a linear speed of conveying a sheet with a nip portion of each roller pair is the same, an input rotation number is different if the roller radius of the driving roller of each roller pair is different. It is therefore difficult to judge a relative comparison between roller peripheral speeds of adjacent roller pairs on the upstream and downstream sides. There is a case wherein an error of input numerical values is found after analysis calculations by numerical time integral.
The confirmation works are further made complicated for a model having time sequentially different sheet conveying speeds and sheet conveying directions, such as a case wherein a sheet is conveyed at 200 mm/s to a certain time, the speed is increased to 400 mm/s from a certain time, and after conveying is stopped for a certain time period, the sheet conveying direction is reversed and then the sheet is conveyed at 600 mm/s.
As described above, it is difficult to grasp time sequentially, visually and intuitively the rotation directions and peripheral speeds of all rollers in a model with drive definitions.